Granted Patent B2

US 6,932,874 · App. 10/690,850 · Granted Aug 23, 2005

Abstract

Claims (16)

1. A method for producing a superconductor having a high copper to superconductor composition (Cu/SC) ratio by cross-sectional area, comprising in sequence the steps of:

(a) preparing by a sequence of operations which include one or more drawing steps, an assembly formed of one or more fine filaments of a NbTi superconductor composition or of Nb as a precursor component for a Nb 3 Sn superconductor alloy composition, which filaments are embedded in a copper-based matrix; and

(b) without subjecting said assembly to a prior heating step to diffuse an alloying element into said filaments, electroplating the assembly from step (a) with copper to increase the Cu/filament ratio by cross-sectional area in the resulting product, and thereby increase the said Cu/SC ratio to improve the stability of the final superconductor; and

(c) subsequent to step (b) heat diffusing said alloying element into said filaments in the instance where said filaments comprise Nb 3 Sn said superconductor precursor and said matrix includes Sn as said alloying element for said Nb 3 Sn superconductor composition, said heat diffusing being conducted while preventing diffusion of said Sn alloying element into the said electroplated copper by means of a diffusion barrier layer, and wherein when said diffusion to form Nb 3 Sn is carried out said electroplated assembly is in the form of a magnet.

2. The method of claim 1 , wherein the superconductor comprises NbTi.

3. The method of claim 1 , wherein the Cu/filament ratio by area in the product of step (a) is from about 0.5 to 3 and wherein the Cu/SC ratio in the final product resulting from said method is from about 2.0 to 5.0.

4. The method of claim 3 , wherein said Cu/filament cross-sectional area ratio in the product of step (a) is from about 0.5 to 1.5.

5. The method of claim 4 , wherein said one more filaments comprise Nb which in step (c) is reacted with Sn contained in said matrix to form Nb 3 Sn.

6. The method of claim 4 , wherein the superconductor or precursor component in step (a) is a single core wire and the said Cu/filament cross-sectional area ratio in the product of step (a) is from about 0.5 to 1.0.

7. The method of claim 6 , wherein said core wire is NbTi.

8. The method of claim 4 , wherein the superconductor or precursor component in step (a) is a multifilament wire wherein the Cu/filament cross-sectional area ratio is at least 1.0.

9. The method of claim 8 , wherein said multifilaments comprise said NbTi superconductor composition.

10. The method of claim 8 , wherein said filaments comprise Nb which in step (c) is reacted with Sn contained in said matrix to form Nb 3 Sn.

11. The method of claim 1 , wherein the current density used in step (b) for electroplating is at least 300 amp/ft 2 .

12. The method of claim 1 , wherein the product of step (b) is subjected to further processing.

13. The method of claim 1 , wherein the product of step (b) is subjected to a metal working step prior to step (c).

Assignments (9)